The GCF is 2.
If that's 21, 78 and 32, the GCF is 1. If that's 2178 and 32, the GCF is 2.
The GCF is 26.
The GCF is 6.
The GCF is 3.
The GCF is 26.
The GCF is 2.
The GCF of 78 and 30 is 6.
The GCF is 1.
The GCF is 2.
The GCF is 3.
The GCF is 2.
gcf(100, 78) = 2